The federal government believes a terrorist attack at the U.S.-Mexico border is imminent and has put out a bulletin on the matter, a government watchdog group reported Friday.

Judicial Watch released a statement that said Islamic terrorist groups who have infiltrated the city of Ciudad Juarez aim to use car bombs to attack American interests.

“High-level federal law enforcement, intelligence and other sources have confirmed to Judicial Watch that a warning bulletin for an imminent terrorist attack on the border has been issued,” the statement read. “Agents across a number of Homeland Security, Justice and Defense agencies have all been placed on alert and instructed to aggressively work all possible leads and sources concerning this imminent terrorist threat.”

High-level sources in the intelligence community told the nonprofit organization that one of the terrorist groups operating out of Ciudad Juarez is the Islamic State, which beheaded American photojournalist James Foley earlier this month. The radical Sunnis, led by Abu Bakr al-Baghdadi, also control large swathes of Iraq and Syria.

Shortly after the government watchdog story was released, a spokesman for the Department of Homeland Security denied the report, saying “we are aware of absolutely nothing credible to substantiate this claim,” the Daily Mail reported.

White House Press Secretary Josh Earnest also responded, saying that “the most detailed intelligence assessment that I can offer from here is that there is no evidence or indication right now that [the Islamic State group] is actively plotting to attack the United States homeland. That’s true right now,” the paper reported.

Judicial Watch president Tom Fitton stood by the story, telling the Daily Mail that the government’s denial constitutes a “non-denial denial” that is “so dishonest.” He added that his sources were “golden.”

Mr. Fitton said the use of the words “credible” and “specific” were rhetorical loopholes that one “could drive a truck bomb through,” the paper reported.

News of the bulletin comes just one day after U.S. officials told The Blaze there has been a “significant increase” in chatter among terrorist groups as the 13th anniversary of the Sept. 11, 2001, terrorist attacks nears.